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Acoustic b450 mkII

Discussion in 'Amps and Cabs [BG]' started by gigadude7, Apr 2, 2013.

  1. gigadude7


    Apr 2, 2013
    Okay, I have a few questions about my amp.


    1) What does it mean by, "450 Watts (stand-alone), 600 Watts (w/extension speaker)?"

    2) What in the heck is a, "High-Frequency horn driver with defeat switch?"

    3) It says you can control the compressor and overdrive with a footswitch but I don't know how to do that. Do I need some additional hardware?

    Thanks for the help!
  2. LoTone

    LoTone Clean as an Entwistle... Gold Supporting Member

    Nov 4, 2010
    Quebec, Canada

    I might help.

    1) This means that the combo by itself will push 450W through the built-in 2x10 speakers. If you had a second cabinet with an impedance of 8 ohm, the head will push an extra 150W out, for 600W total, across the built-in speakers in the combo and the external cabinet.

    2) Your combo has 2x10 inch speakers plus a tweeter. The tweeter is the little speaker in the top left corner. A tweeter is also called a high-frequency horn because it is designed to output high frequencies. In the back of the combo, there is an on/off switch that allows you to turn off the horn. Why would you turn the horn off? You might want to turn the horn off, if you want to have a warmer, rounder, old-school sound. Also, sometimes, depending if you boost the treble, you might here some hiss or distortion at high volume.

    3) You can buy an extra footswitch. That footswitch has two toggle switches. One allows to engage/disengage the overdrive section. The other switch allows you to engage/disengage the effects loop.

    I suggest that you look at the manual at:



  3. gigadude7


    Apr 2, 2013
    Thank you so much!

    So if I used a B410 400w 4x10 Bass Cabinet in addition to the b450mkII, then I would only get 600w instead of 1000w?

    Also, what would the footswitch look like/where could I buy one?
  4. It is the amplifier that "produces" wattage. Speakers do not "produce" wattage, they take the power produced by the amp and convert it to sound.
  5. gigadude7


    Apr 2, 2013
    So I would only get the 600w of sound?
  6. You would get 600 watts of amp power. That 600 watts put into six 10"s instead of two will be way louder (sound). Watts and sound are not equal. Watts are the ability to do work, more speakers use that power more efficiently to convert that power to sound.
    200 watts going into six 10" speakers will be louder than 600 watts into two of the same 10" speakers.
  7. gigadude7


    Apr 2, 2013
    Okay thanks. That clears up a bunch of questions.
  8. Cool!
  9. Kevin Colt

    Kevin Colt

    Feb 9, 2015
    Bokeelia, Fl.
    I have a b 450 mk II. the p.t. took a dump. they're not available from acoustic as a replacement part. it is toroidal transformer. I bought one with what I thought was the same parameters but after I installed it, all I get is a 120 hz hum out of it. I just found the schematics for it online. these may help me figure out what is wrong and correct it. only time will tell. maybe it will help someone else.

    Attached Files:

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